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Raid/No Raid

Discussion in 'General Discussion' started by procam, Nov 15, 2006.

  1. procam

    procam Well-Known Member

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    I have been bothered by this for a LONG time now and I would like some other peoples opinions~

    I have units running with various raid configurations and I have units with no raid at all.

    But...... Im getting ready to put a new unit up with a 6 drive setup and I simply cannot make up my mind raid or no raid and I would very much like to do it with no raid but I cant work it out in my head...........

    If you have
    1 Drive for OS
    2 Drives for /home /home2
    That would leave 3 for backup data
    BUT thats where I just got in trouble - I cant figure out how I would tell cpanel to use all 3 drives for backup data unless I just ran those 3 as a 1 raid drive and had cpanel write to it as /backup for example

    I really dont want to do another full raid setup its proven to either be too slow or too problematic when a drive does fail even with hotswapping something always seems to screw up.

    Opinions?

    A nice feature change to the backup option in cpanel might be
    Drive 1-4 mount name and then the ability to specify user accounts to each drive like a-g drive 1 and so on .........
     
  2. AndyReed

    AndyReed Well-Known Member
    PartnerNOC

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    As you may know, RAID, which can be implemented in hardware or software (RHE gives you this option), spreads data a cross multiple disks. Depending on which level you choose, RAID can provide data redundancy to protect the data in the case of hardware failure. Although it can also improve disk performance by increasing read/write speed, RAID uses quite a bit of CPU time, which may be a consideration in some situations.

    I suggest you do NOT do not use RAID as a replacement for regular backups. If your system undergoes a catastrophic failure, RAID will be useless. RAID also doesn't take care of something as simple as replacing a file when you delete it by accident. In these cases, a backup on a removable medium (that has been removed) is the only way you will be able to restore a file system. Good luck!
     
  3. Lyttek

    Lyttek Well-Known Member

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    I don't they were planning on replacing backups with raid, rather storing backups on a raid array made up of three disks, which is fine.

    If one drive fails, you can still rebuild your backups. Depending on how raid is implemented (hardware/software) you may or may not see a general system slowdown while the array is rebuilt.

    I prefer running raid 1 (mirroring) as opposed to raid 5 (striping) because there it's easier to rebuild from... a dead drive doesn't affect performance immediately, so I can schedule a rebuild for the off-hours.
     
  4. jsnape

    jsnape Well-Known Member

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    RAID1 wont be a hit on performance at all. But I wouldn't suggest software raid1. Performance (in my tests) is the exact same, but in the case of power loss RAID1 (software) has a good chance of being destroyed. And I mean GOOD chance. Had it happen 3 times
     
  5. Lyttek

    Lyttek Well-Known Member

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    CMIIW, but software RAID of any type can have issues during a power loss... so can hardware RAID for that matter...

    Power loss isn't fun, regardless of what system you're using ;)
     
  6. nyjimbo

    nyjimbo Well-Known Member

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    Has anyone here truly gone through a catastrophic failure of one drive on a RAID 1 running Cpanel and recovered cleanly from it ?.

    I know how it's supposed to work, but what did you experience, what did it look like, what steps did you take to recover and how long did it take?.

    We backup the hell out of our servers and keep multiple copies on both mounted drives as well as rync'd .TAR files of paritiions AND also swap our backup drives monthly to have even more redundancy, but the RAID thing sounds like a painless recovery from a dead drive, but it would be nice to hear a real world experience from a web host running cpanel.
     
  7. jsnape

    jsnape Well-Known Member

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    If you mean having a drive fail on a system set up with raid1, yes, twice last week. Both servers brand new, w/ new drives, hot swap enabled. A western digital 500gb and seagate 320gb. Recovering from it didn't require powering down, just pulling the old one and sliding in a new one and watching 3ware detect it and rebuild it with no intervention whatsoever.

    Can't complain about the seagates, but almost can. So far 3 out of a batch of 24 new drives failed in the first month. Western digital 1 out of 2. Hitach 0 out of 4. The western digitals were more of a test to verify that they still suck, and they passed the test.
     
  8. Lyttek

    Lyttek Well-Known Member

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    Do you suppose that's a good review: that they met your expectations? :p
     
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